Clean storage packaging article and method for making and using

ABSTRACT

A packing article for the storage and/or transport of items and materials requiring high levels of cleanliness is described. Methods of making and using the packaging article are also described. The packaging article may be used to store or transport, for example, advanced optical components, or materials and components used in the manufacturing of microelectronic devices or optical components. A method of making the packaging article includes contacting the packaging article with organic solvent(s) and acidic solution(s) and rinsing with ultrapure water. Interior cleanliness levels for various contaminants, such as, metals, anionic materials, organic compounds, and particles may be verified and the packaging articles may be labeled and sorted according to cleanliness level.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of U.S. application Ser. No.13/630,129 filed Sep. 28, 2012, herein incorporated by reference in itsentirety for all purposes.

BACKGROUND Field

The present disclosure relates to a packaging article for the storageand/or transport of items and materials requiring high levels ofcleanliness.

Description of the Related Art

Semiconductor and microelectronic devices, components, andsub-assemblies are well known examples of items requiring high levels ofcleanliness during their manufacture. Semiconductor and microelectronicdevices are generally manufactured in special facilities known as“cleanrooms.” Cleanrooms are carefully controlled environments in whichspecial precautions are taken to limit airborne particles andcontaminants. These precautions include, amongst other things,constantly filtering the cleanroom atmosphere, requiring workers to wearspecial garments while in the cleanroom, and limiting materials allowedinto the cleanroom. For example, it is common cleanroom procedure not toallow items such as pencils, paper, chalk, cosmetics, or cardboardinside the cleanroom because these items shed particles or generatedust.

Cleanrooms are expensive to build and maintain, but the expense isnecessary since it is well known that even small increases in particleand contaminant levels present during manufacturing may adversely affectprocess yield and device performance. As integrated circuit featuredimensions have decreased, cleanliness has become even more critical,so, accordingly, additional efforts have been made to improvecleanrooms. Improved air filtering, tighter controls on allowablematerials, and better cleanroom garments for workers have all beenpursued, and today cleanrooms with fewer than ten particles (of a sizegreater than a half micron) per cubic foot are common.

But increasingly, the process for manufacturing semiconductor devicesinvolves multiple facilities, each of which might be separated bythousands of miles. A manufacturer may perform certain processing stepsat a specialized plant located in North America, and then ship partiallycompleted wafers to another plant in Europe or Asia for completion andfinal processing into individual microchips. Or the manufacturingprocess may require materials, equipment, and component parts to beshipped between clean facilities. Shipping intermediate components andmaterials from one manufacturing facility to another means componentsand materials must be removed from the protection of the carefullycontrolled cleanroom environment and may therefore face possiblecontamination unless suitably protected. Therefore, a need exists for apackaging solution for items and materials requiring high levels ofcleanliness.

SUMMARY

It is an object of the present disclosure to provide an economicalstorage solution for clean items and materials. In one embodiment, thestorage solution comprises a packaging article of fluoropolymercomposition that has been cleaned to remove contaminants and particlesgenerated by its manufacture or subsequent handling. A method ofmanufacturing clean packaging articles and a method of using cleanpackaging articles for the storage and transport of items is alsodisclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe various aspects, briefly summarized above, may be had by referenceto example embodiments, some of which are illustrated in the appendeddrawings. It is to be noted, however, that the appended drawingsillustrate only typical embodiments of this disclosure and are thereforenot to be considered limiting of its scope, for the disclosure may admitto other equally effective embodiments.

FIG. 1. A depiction of an example embodiment of a packaging articleaccording to the present disclosure.

FIG. 2. A depiction of an embodiment of a packaging article label.

FIG. 3. A flowchart depicting an example embodiment of a process forcleaning packaging articles.

FIG. 4. A schematic overview of an embodiment of the cleaning method.

FIG. 5. An example embodiment of the present disclosure showing afluoropolymer packaging article being used to store clean items.

DETAILED DESCRIPTION

Embodiments disclosed herein provide a packaging article particularlyadapted for items and materials requiring high levels of cleanliness. Byway of example, certain embodiments may be described by reference topotential uses in the semiconductor industry, but the present disclosureis not limited to such specific uses.

In the semiconductor industry, shipping or storing an intermediatedevice component typically involves placing it in a protective storagecontainer, for silicon wafers these containers are usually speciallydesigned wafer carriers. The protective storage container is then sealedwithin a plastic bag. This plastic bag is sometimes referred to as an“inner packaging bag,” and generally corresponds to an embodiment of thepackaging article of this disclosure. The inner packaging bag willgenerally be placed inside an additional outer container, such asanother plastic bag, before complete removal from the cleanroomenvironment. This additional outer container generally corresponds to anembodiment of the packaging article of this disclosure. Once outside thecleanroom environment, the inner packaging bag and the storage containermay then be placed in an additional shipping container or containers,such as a shipping crate or box suitable for transport or warehousing.

When bringing items that have been shipped or stored outside of acleanroom back into a cleanroom, the common procedure is to remove theshipping containers (the crates/boxes) in a loading area outside of thecleanroom. The remaining outer container will then be wiped down andcleaned before being taken to a cleanroom antechamber. In theantechamber, the additional outer container may then be removed beforethe remaining inner packaging bag containing the intermediate devicecomponents or materials is taken into the cleanroom. The outer surfaceof the inner packaging bag may be wiped down before the items are passedinto the cleanroom. Only after it is once again inside a cleanroom willthe inner packaging bag be removed and disposed leaving only theprotective storage container.

Inner packaging bags used by the semiconductor industry today are mostcommonly made of nylon or polyethylene. Semiconductor manufacturerscurrently use nylon or polyethylene bags as-supplied without any attemptto clean the bags before use. Nylon and polyethylene bags are relativelyinexpensive, but they also have various surface contaminants, whichgiven the cleanliness standards required by semiconductor devices, maybe detrimental to process yield and device performance.

Contaminant levels of current bags may vary lot-to-lot and/orbag-to-bag, but various organic and metallic contaminants appear to beinherent to making of the bags themselves. Organic contaminants, such asmachine oil residue, may come from the machinery used to form the bagsor from handling of the bags during manufacturing. Even handling of thebags by workers without gloves can impart oils and residues to the bags.Metallic contaminants also may come from the bag making machinery asfriction rubs bits of the machinery into dust. It is well known thatheat welding nylon (for example, to form a bag) generates caprolactam(C₆H₁₁NO) residues which may be a contaminant. Various metallic oranionic compounds may also be present in the nylon and polyethylenematerials themselves as impurities or residual catalyst molecules leftover from various polymer synthetic processes.

Placing components and materials in a packaging article alreadycontaining potential contaminants increases the possibility componentsand materials will become contaminated, as such it would be advantageousto eliminate or reduce such contaminants before the bags are used asinner packaging. To this end, the present disclosure provides packagingarticles for storage/transport of items requiring a high level ofcleanliness, and further provides cleaning methods for producing sucharticles. While such packaging articles may be particularly well-suitedfor storing or transporting semiconductor components, all otherapplications requiring packaging articles of a high level of cleanlinessare contemplated. Therefore, references to the semiconductor industryand semiconductor components are merely illustrative.

Example Packaging Articles

Referring now to FIG. 1, an embodiment of a fluoropolymer packagingarticle 100 is shown. In general, the packaging article 100 includes abody 102 that forms an enclosure 104 sized to accommodate the storage ofan item (e.g., a semiconductor component). The enclosure 104 isaccessible through an opening 106 sized to allow transfer of the item(s)into the enclosure 104. Illustratively, the opening is formed at one endof the body. However, the opening may be formed at other locations, suchas in the middle portion of the body. Further, the packaging article 100may be provisioned with multiple openings.

The body 102 may be made of a fluoropolymer material, such asperfluoroalkoxy (PFA), polytetrafluoroethylene (PTFE), fluorinatedethylene propylene (FEP), perfluoropolyether (PFPE), or polyvinylidenefluoride (PVDF). Fluoropolymers have polymeric repeat units withstructures having fluorine atoms covalently bonded to carbon atoms.Fluoropolymers may be a homopolymer or may be a co-polymer of differentfluorocarbon monomers or fluorocarbon monomers and hydrocarbon monomers.Fluoropolymers may also contain other halogens, such as chlorine, inaddition to fluorine, such as in polychlorotrifluoroethylene (PCTFE) (apolymer formed from chlorotrifluoroethylene). The co-polymers maybealternating, block, or periodic. It should be understood that the abovelist is not exhaustive and other fluoropolymer materials, includingvarious co-polymers involving precursors of the above materials, couldbe suitable as well.

In general, fluoropolymer packaging articles will be more stable in bothorganic solvents and acidic solutions than a packaging article composedof nylon. This stability in organic solvents and acidic solutions allowsfluoropolymer packaging articles to be cleaned according the presentdisclosure to make the fluoropolymer packaging articles suitable forstorage of items or materials requiring high levels of cleanliness.Nylon materials are generally more susceptible to swelling and/ordissolution by organic solvents than a fluoropolymer material would be.And some stronger acidic (nitric acid and sulfuric acid, for example)solutions may even dissolve or breakdown common nylon resins, thus nylonmaterials cannot effectively be cleaned according to embodiments of thepresent disclosure.

Unlike nylon, some polyethylene materials may be relatively stable instronger acidic solutions, as there are many types and variants ofpolyethylene. But commercial grade polyethylene resins (the resins usedto make packaging bags) generally contain residual metallic catalystmolecules, which fluoropolymer resins do not. Any metallic catalystsused in the synthesis of polyethylene materials will generally bepresent in the final articles. This residual catalyst preventspolyethylene materials from being cleaned to levels achieved byfluoropolymer materials. Therefore, a body 102 made of fluoropolymermaterials may be preferred, but other materials are contemplated asalternative embodiments even where the resulting level of cleanliness isrelatively less than what may be achievable with fluoropolymermaterials.

In some embodiments, the body 102 may be rigid or flexible, or partiallyrigid and partially flexible. Further, the body 102 may be opaque ortranslucent or a combination of opaque and translucent, such that, forexample, the packaging article 100 may be generally opaque but have atranslucent window or windows which may function as view ports into theenclosure 104. Body 102 may comprise a single piece or may comprisemultiple pieces joined together.

Body 102 may optionally have a label 108 disposed on an exterior surfaceor otherwise formed in a surface. Label 108 may, for example, be anadhesive label applied to an exterior surface or may be formed into asurface using an embossing, molding, or etching method. Label 108 mayprovide information concerning the packaging article's contents,cleanliness specifications, composition, safe usage, or otherinformation relevant to potential users or handlers of the article. Aparticular example of a label 108 is shown in FIG. 2. Illustratively,the label 108 depicted in FIG. 2 shows four categories of contaminants;namely, measured levels of various anionic, metallic, organic, andparticle contaminants. Each category of contaminants may include one ormore values (e.g., F and CI under “anions”) as well as one or morecleanliness specification (e.g., 1×10¹⁰ Ions/cm², sometimes numbers ofthis sort may be equivalently denoted as 1E10 Ions/cm²). The label 108may include additional information such as trade names, companyinformation, manufacturing and/or certification dates. The labeldepicted in FIG. 2, is an example only and more or less or differentinformation than shown may be incorporated on a label 108.

When label 108 is an adhesive label, such information may be printedonto the label prior to, or after, being affixed to the packagingarticle. In one embodiment, the information is in the form ofalphanumeric characters that can be read directly by a human-being (suchas is exemplified by the label of FIG. 2). Alternatively, the label maybe encoded in some computer readable format, such as a QR code. Anappropriate reader, e.g., QR code scanner, reads the computer readablelabel and displays the package/content information on a display. Instill another embodiment, the label is stored on an RFID disposed on thebody 102. An RFID reader is brought into the vicinity of the tag to readand display the label information.

The packaging article 100 may be formed and/or sealed using heat weldingmethods. Energy for welding may be supplied by a variety of methodsincluding heated metals, infrared light, lasers, ultrasound, ormicrowaves. Other welding methods, such as solvent welding, may also beused to seal or form the packaging article without departing from thescope of this disclosure. Rather than (or in addition to) welds, body102 may be sealed and/or formed using adhesives or mechanical fasteners,such as clamps, clips, ties, screws, rivets, or the like. The methodused to seal and/or form the packaging article 100 may be temporary,such as with a folding and clamping method when the packaging articlehas flexible portions, or may be of more permanent nature such as with aweld. A mechanical sealing mechanism such as a zipper or frictionsealing methods commonly found in food storage bags may be optionallyincorporated for sealing opening 106, but this would generally not bepreferred since friction sealing methods will generate additionalparticles with each opening and closing of the mechanism, which mightcompromise the cleanliness of the packaging article.

In a particular embodiment, the packaging article 100 may be in the formof a bag. A bag for purposes of this disclosure encompasses anypackaging article formed primarily of a flexible plastic in which anitem or material can be placed and then substantially sealed from theoutside environment within an enclosure region. An open bag has anopening or openings through which items and materials can be insertedinto or removed from the enclosure or pocket region. A closed bag is anopen bag that has had its opening or openings sealed. Sealing may beaccomplished by a variety of means and may, but need not, achievehermetic or air tight enclosure.

A bag may be formed in a variety of ways. For example, the bag maycomprise a single plastic sheet folded upon itself and welded along itsoverlapping edges to form the enclosure 104. The bag could be formed byfolding a single rectangular sheet once upon itself at a pointapproximately midway between two corners and welding two of theresultant three overlapping sides. Or an open rectangular bag could beformed by welding two stacked rectangular sheets along three sides ofthe rectangle. A closed rectangular bag could be formed by welding twostacked rectangular sheets along four sides of the rectangle. An opening106 could then be formed by cutting into the closed bag. A bag may alsobe formed out of non-rectangular sheets, such as circular, polygon, orirregular shaped sheets, by similar edge welding and/or folding methods.

Optionally, the bag may comprise multiple sheets arranged in layers suchthat each wall of the enclosure 104 is formed of multiple layers. Thebag may be provided with pleats or folds allowing expansion of theenclosure 104 to accommodate the placement of items within. The bag mayfurther include a label 108 for providing information to potential usersor handlers of the bag.

Example Cleaning Methods

To lower the particle and contaminant counts and make the packagingarticle suitable for storage of items requiring high levels ofcleanliness, the packaging article 100 may be subjected to cleaningsteps designed to reduce organic, metallic, and/or anionic residues orimpurities on the article's surfaces. In one aspect, the disclosedcleaning process may also work to improve overall particle counts withinthe packaging article.

An example embodiment of a multi-step cleaning process (process 300) forfluoropolymer packaging articles is schematically depicted in FIG. 3.The example cleaning process begins with an organic solvent wash (step302). The organic solvent used for this wash step could be pureisopropyl alcohol (IPA), for example, but other organic solvents, suchas acetone, benzene, and methanol, may be selected provided the selectedsolvent does not dissolve, react with, or significantly swell thefluoropolymer resin comprising the packaging article. Fluoropolymers arewell known for their ability to withstand organic solvents, so a widevariety of potential organic solvents are available. Rather than being asingle organic solvent, the organic solvent wash may comprise admixturesof different organic solvents in various ratios or may comprise asequence of organic solvents applied one after another. In general, theorganic solvent (or solvents) selected should have low particle countsand not add significantly to metallic or anionic contaminants alreadypresent on the packaging article.

After the solvent wash, the packaging article is rinsed (step 304). Inone embodiment, this rinse step may be performed with ultrapure water(UPW). UPW may also be referred to as “de-ionized and filtered water.”UPW should be understood to include any high purity water of a typesuitable for semiconductor processing. The rinse may comprise a bath,soak, or leach process or may comprise continuously flowing UPW over thesurfaces of the packaging article. The rinse step may comprise a singlerinse or sequence of individual rinses one after the other with therinse water disposed of between individual rinses. The rinse step maycomprise a combination of individual baths, soaks, leaches, or flowingwater steps. The rinse step may involve agitation, including potentiallyultrasonic agitation.

Next, the packaging article is exposed to an acidic solution wash (step306). The acidic solution wash is intended to extract or removemetallic/anionic contaminants, so acids should preferably be selectedsuch that they are capable of bringing target contaminants intosolution. Solubility of metal ions in various acid solutions isavailable in standard chemistry literature. Thus, it is contemplatedthat the acidic solution wash may comprise a variety of potential acidsand concentrations. It is also contemplated, that the packaging articlemay be exposed to a sequence of separate and chemically different acidicsolutions. In a particular example, the acidic solution could be 1%(w/w) aqueous nitric acid (HNO₃). As an example of a mixture of acids,the well-known mixture of sulfuric and nitric acids (“aqua regia”) thatdissolves gold and platinum could be used. The acidic solution couldalso include additional components such as hydrogen peroxide (H₂O₂) topromote oxidation of organic contaminants, such as in the mixture ofsulfuric acid (H₂SO₄) and hydrogen peroxide commonly referred to as“piranha etch.”

The acidic solution wash is followed by a second rinse (step 308), whichmay be performed according to the general description above for thefirst rinse step (step 304). But it should be noted that the first andsecond rinse steps need not be performed in an identical manner.

The packaging article is then dried (step 310). The drying process mayinvolve air drying (evaporation) in a filtered environment. But vacuumovens, forced air/gas drying, heating and the like may also be used. Thepackaging article may be continuously or intermittently rotated, shaken,or otherwise agitated during the drying process. Alternatively, thepackaging article may be left stationary and particle filtered air/gasmay be blown over the surfaces of the packing article.

If desired, the cleaning steps can be repeated. The order of the solventwash and the acidic solution could be reversed, but this is generallynot preferred because certain organic surface contaminants, say an oilysmudge, might prevent an aqueous acid solution from fully scouring thepackaging article's surface for metal/anionic contaminants.

Wash steps (steps 302 and 306) involve bringing the packaging articleinto contact with a solvent/solution and such contact may comprise soaksor leaches wherein the solvent or acidic solution is left in stagnantcontact with the packaging article's surfaces. Or wash steps may involveagitation of the wash fluid by stirring or shaking or the like. Washsteps may also comprise continuous flows of solvent or acid solutionsover the packaging article's surfaces, such as, for example, in a showerapparatus. The wash steps may comprise sequences or combinations ofsoaks, leaches, agitations, or showers.

Solvent and/or acid solutions may be changed or renewed after eachpackaging article is washed or several packaging articles may be washedin sequence in the same bath/shower before the solvent or solution ischanged (though the effectiveness of a wash solvent or solution would beexpected to degrade with repeated use). Several packaging articles mayalso be washed at the same time in a single tank, bath, or shower, ifdesired.

After the cleaning process, contaminant and particle counts remaining onthe packaging article's interior surfaces can, optionally, be measuredby performing various analytical tests on rinse (or wipe) samples fromthe packaging article's surfaces (step 312). For example, a laserparticle counter can give a particle count and particle sizedistribution and various chromatography techniques can be used toestimate remaining levels of organic, metallic or anionic contaminants.The various analytic results can then be used to sort packaging articles(or packaging article lots) by cleanliness, such that the cleanestpackaging articles can be reserved for the most contaminant sensitive orimportant applications.

A specific example embodiment of the cleaning process 300 is describedas follows, with reference to FIG. 4: First, a fluoropolymer bag 402,for example a PVDF bag, is obtained. In this example embodiment, theorganic wash step (step 302) comprises two separate stagnant leach steps(410 and 420). For the first leach step bag is filled with IPA until itis approximately half full or more. The bag is then folded and clampedso as to prevent the liquid (IPA) from escaping the bag, as depicted inFIG. 4. The IPA is left to sit in the bag for a time exceeding 60minutes. After the elapsed time, the bag is then rotated and/or flippedsuch that the any portions of the bag interior not initially in contactwith the IPA are brought into contact with the IPA and the secondstagnant leach step 420 is started. The IPA is left to sit in therotated/flipped bag for a time exceeding 60 minutes. The organic washstep is completed when the IPA is emptied from the bag in to a wastedisposal collection system 430. The length of the stagnant leach stepsin this example is 60 minutes or more, but this time is only an exampleand the time may be less than 60 minutes in some circumstances. Thelength of the leach step may vary in length according to initialcleanliness of the bag, solvent type, temperature, or other processparameters.

The rinse step (step 304) is, in this embodiment, a sequence of threeseparate rinses with UPW (a “triple rinse”). For each individual rinse(440), UPW is applied to the interior surfaces of the bag and thendisposed. As stated, this is done three times before the next wash step(step 306) is started.

In this example embodiment, the acidic solution wash (step 306) isperformed following the organic solvent wash step (step 302) and therinse step (step 304). The acidic solution wash (step 306) in thisexample comprises two separate stagnant leach steps (450 and 460). Tobegin the acidic solution wash, the bag is partially filledapproximately half full with an aqueous nitric acid solution (1% (w/w)).The bag is then again folded and clamped, as depicted in FIG. 4. The bagis left to sit for no less than 60 minutes. After the elapsed time hasbeen met, the bag is then rotated and/or flipped such that the anyportions of the bag interior not initially in contact with the acidicsolution are brought into contact with the acidic solution. The nitricacid solution is then left to sit in the rotated/flipped bag for a timeexceeding 60 minutes. This acidic solution wash step is completed whenthe nitric acid solution is emptied from the bag and disposed. Thelength of the stagnant leach steps in this example is 60 minutes ormore, but this time is only an example and the time may be less than 60minutes in some circumstances. The length of the leach step may vary inlength according to initial cleanliness of the bag, solvent type,temperature, or other process parameters.

After the acidic solution wash step of this embodiment, the bag is againrinsed in a rinse step (step 308) with UPW similar to the previous rinsestep (step 306) after the organic solvent wash. In this example, thissecond rinse step is, like the first rinse step, a triple rinse withUPW. For each individual rinse (470), UPW is applied to the interiorsurfaces of the bag and then disposed. As stated, this is done threetimes before the drying (step 310) is started.

After the second rinse step, the bag is placed in a high efficiencyparticulate air (“HEPA”) filtered laminar flow hood 480 to dry overtime. A HEPA-filtered laminar flow hood is sometimes referred to as a“clean hood.” The bag may be placed in the hood with its opening eitherfacing the flow of filtered air or may be placed with its opening facingaway from the flow. To speed drying, the bag may be clamped orrestrained such that its interior is substantially open such that bagsidewalls are not in significant contact. Multiple bags may be placed inthe drying apparatus simultaneously or they may be dried in sequence.

If desired, the effectiveness of the described example cleaning processmay be evaluated with various analytical techniques (step 312). Tracemetals may be measured by, for example, ICP-MS (Inductively CoupledPlasma Mass Spectrometry) on sample drawn from a nitric acid solutionrinse. Organic contaminants may be measured by GC-MS (GasChromatography-Mass Spectrometry) on a sample drawn from an IPA rinse.Anionic contaminants may be measured by ion chromatography on an UPWrinse. Overall particle counts may be evaluated using a laser particlecounter to measure particles extracted from the bag in a UPW rinse.Particle and contaminate counts are generally measured per unit of bagsurface area (cm²), so the analytic samples must be taken from a knownsurface area.

Additional, contaminants, including biologically relevant counts such asmicrobe levels, may be measured and collected without departing from thespirit of this disclosure. The listed contaminant types and analyticmethods are by way of example only. More or fewer categories ofcontaminants may be relevant to some applications. And differentanalytic methods may be capable of producing similar or equivalentmeasurements for certain contaminant types.

Individual packaging articles may optionally be sorted according tospecific analytic test results. Or rather than individual test results,statistically significant samples from a specific cleaning lot may beused to sort packaging articles according to cleanliness level.Packaging articles may be sorted by level of cleanliness into groupscorresponding to levels appropriate for intended uses. For example,packaging articles may be sorted by cleanliness levels (or ranges ofcleanliness levels) into classes suitable for different semiconductordesign nodes (e.g., 45 nm node, 22 nm node, or 14 nm node). Thepackaging articles may also (or instead) be sorted by levels of specificcontaminants, such that, for example, packaging articles with the lowestoverall particle counts may be reserved for usage with advanced opticalcomponents, while packaging articles with the lowest levels of ametallic contaminates may be reserved for use with semiconductor deviceswith long operational lifetime requirements or mission criticalapplications, such as microcontroller units in medical devices.

Example Uses

After cleaning, the fluoropolymer packaging article can be used to storeand transport clean items, for example advanced optical components.Clean items or materials can be inserted through opening 106 and placedinside enclosure 104 of body 102. The packaging article may optionallybe sealed using a method such as folding, clamping, taping, applyingadhesives, welding, or the like.

In a particular embodiment of the present disclosure, packaging article100 may be in the form of a fluoropolymer bag to be used as innerpackaging bag for the transport of semiconductor device components, suchas silicon wafers, or advanced optical components. Referring now to FIG.5, a body 102 is in the form of a bag. The bag comprises a flexiblefluoropolymer, for example PVDF, sheet folded along fold 506 and weldedalong welds 504, leaving opening 106. Silicon wafers or advanced opticalcomponents 502 (inside a wafer carrier) can be inserted into packagingarticle 100 through opening 106. Once silicon wafers or advanced opticalcomponents 502 are placed inside packaging article 100, the bag may beclosed with sealing weld 508. Sealing weld 508 may be formed by heatwelding or other methods previously discussed. Optional label 108 may beplaced on the bag. Optional label 108 may in some embodiments haveinformation provided as shown on the label depicted in FIG. 2.

Experimental Data

Uncleaned PVDF bags were obtained from a commercial vendor. Forcomparison purposes, a nylon bag marketed as suitable for use as aninner packaging bag for semiconductor industry applications was alsoobtained from a commercial vendor. One uncleaned PVDF bag was set asidefor later comparison testing. One uncleaned bag was cleaned according tothe method described above in reference to FIG. 4. Specifically, thecleaning method involved stagnant leach steps each lasting 60 minutes.That is, the IPA leach steps 410 and 420 each lasted for 60 minutes. Andthe nitric acid leach steps 450 and 460 also each lasted for 60 minutes.The cleaned PVDF bag was dried in the clean hood while clamped in anopen position with the opening facing into the laminar flow of the cleanhood. All other steps were as otherwise previously described inreference to FIG. 4.

The as-supplied nylon bag, the as-supplied uncleaned PVDF bag, and thecleaned PVDF bag were subjected to various analytical tests. Metalliccontaminant and particle counts for these bags were as stated in Table 1and Table 2, respectively. The results show that the as-supplied PVDFbag has generally higher metal contaminant levels (cleanliness levels)than the as-supplied nylon bag. But unlike the nylon bag commonly usedtoday, a PVDF bag can be cleaned according to an embodiment of thepresent invention to make the PVDF bag suitable for storage andtransport of clean items. As shown in Table 1 and Table 2, the cleanedPVDF bag has contaminant and particle levels superior to the nylon bagand the uncleaned PVDF bag.

Metal contaminant counts reported in Table 1 were measured using ICP-MSperformed on rinse samples taken from the interior surfaces of theexemplar bags. The rinse was performed using 1% (w/w) aqueous nitricacid solutions. Other metals may be measured as required.

Particle counts (cleanliness levels) reported in Table 2 were measuredusing a laser particle counter on rinse samples taken for the interiorsurfaces of the exemplar bags. The rinse was performed using UPW.

The reported levels for nylon are for a standard nylon bag commerciallyavailable; the results are believed to be representative, butsubstantial variation bag-to-bag and lot-to-lot may be expected amongstsuch bags. Likewise the results reported for the pre-cleaned PVDF arebelieved to be representative of such bags, but substantial variationbag-to-bag and lot-to-lot may be expected amongst such bags.

Table 3 provides the results of measurements of the organiccontamination levels (cleanliness levels) for a cleaned PVDF bag. Thecleaned PVDF bag measured less than 1 nanogram/cm² (1×10⁻⁹ gram/cm²)apiece of “low boilers” (carbon-containing compounds with seven to tencarbon atoms), “medium boilers” (carbon-containing compounds with elevento twenty carbon atoms), and “high boilers” (carbon-containing compoundswith greater than twenty carbon atoms). Organic contaminant levelsreported in Table 3 were measured using gas chromatography-massspectroscopy (GC-MS) on rinse samples taken from the interior surface ofa cleaned PVDF bag. The rinse was performed using isopropyl alcohol(IPA).

Table 4 provides the results of measurements of the anioniccontamination levels (cleanliness levels) for a cleaned PVDF bag. Thecleaned PVDF bag measured 1×10¹⁰ anion/cm² or less for fluoride (F⁻),chloride (Cl⁻) nitrite (NO₂ ⁻), sulfate (SO₄ ²⁻), and phosphate (HPO₄²⁻) anions. Anionic contaminant levels reported in Table 4 were measuredusing ion chromatography on rinse samples taken from the interiorsurface of a cleaned PVDF bag. The rinse was performed using UPW.

TABLE 1 Metal Contaminants for example nylon bag and a PVDF bag beforeand after cleaning. PVDF PVDF Contaminant Nylon (Pre-clean) (Post-clean)Aluminum 40 130 <1 (1 × 10¹⁰ atoms/cm²) Calcium 120 280 <1 (1 × 10¹⁰atoms/cm²) Copper 15 4 <1 (1 × 10¹⁰ atoms/cm²) Iron 3 42 <1 (1 × 10¹⁰atoms/cm²) Magnesium 19 49 <1 (1 × 10¹⁰ atoms/cm²) Potassium 60 36 <1 (1× 10¹⁰ atoms/cm²) Sodium 170 490 <1 (1 × 10¹⁰ atoms/cm²) Zinc 6 14 <1 (1× 10¹⁰ atoms/cm²)

TABLE 2 Particle counts by particle size for an example pre- andpost-clean PVDF bag. Count units are particles/cm² (of bag interiorsurface area). PVDF PVDF Particle Size (Pre-clean) (Post-clean) >0.3 μm96.3 19.1 >0.5 μm 15.2 3.0 >1 μm 2.4 0.1 >5 μm 0.4 0.0

TABLE 3 Organic contamination levels for a post-clean PVDF bag. Levelsare reported per unit area (of bag interior surface area). OrganicCompound Post Clean Level Low Boilers (C7-C10) <1 × 10⁻⁹ g/cm² MediumBoilers (C11-C20) <1 × 10⁻⁹ g/cm² High Boilers (greater than C20) <1 ×10⁻⁹ g/cm²

TABLE 4 Anionic contamination levels for a post-clean PVDF bag. Levelsare reported per unit area (of bag interior surface area). Anion PostClean Level Fluoride <1 x 10¹⁰ ion/cm² Chloride   1 x 10¹⁰ ion/cm²Nitrite <1 x 10¹⁰ ion/cm² Sulfate <1 x 10¹⁰ ion/cm² Phosphate <1 x 10¹⁰ion/cm²

It will be understood that many additional changes in the details,materials, steps, and arrangement of parts, which have been hereindescribed and illustrated in order to explain the nature of theinvention, may be made by those skilled in the art within the principleand scope of the invention as expressed in the appended claims. Thus,the present invention is not intended to be limited to the specificembodiments in the examples given above and/or the attached drawings.

What is claimed is:
 1. A packaging article for storage of clean items,comprising: a body made of a material comprising a fluoropolymer, thebody forming an enclosure sized to accommodate a clean item and havingat least one opening to the enclosure, the opening adapted to receivethe clean item therethrough; and an interior surface of the body, theinterior surface having: less than 1×10¹⁰ atoms/cm² of each of thefollowing metals: aluminum, calcium, copper, iron, magnesium, potassium,sodium, and zinc; less than 1×10¹⁰ ions/cm² for each of the followinganions: fluoride, chloride, nitrite, sulfate, and phosphate; and lessthan 2 nanogram/cm² of each of the following organic compounds:compounds with seven to ten carbon atoms, compounds with eleven totwenty carbon atoms, and compounds with greater than 20 carbon atoms,the packaging article produced by placing the packaging article incontact with a solution comprising an organic solvent, rinsing thepackaging article with ultrapure water; placing the packaging article incontact with an acid solution, rinsing the packaging article withultrapure water; and drying the packaging article.
 2. The packagingarticle of claim 1, wherein the interior surface of the packagingarticle further has: less than 1 nanogram/cm² of each of the followingorganic compounds: compounds with seven to ten carbon atoms, compoundswith eleven to twenty carbon atoms, compounds with greater than 20carbon atoms; less than 1 particle/cm² for particles greater than 5micron in size; less than 10 particles/cm² for particles 1 micron to 5micron in size; and less than 100 particles/cm² for particles 0.5 micronto 1 micron in size.
 3. The packaging article of claim 2, wherein thefluoropolymer material is selected from the group consisting ofperfluoroalkoxy (PFA), polytetrafluoroethylene (PTFE), fluorinatedethylene propylene (FEP), perfluoropolyether (PFPE), and polyvinylidenefluoride (PVDF).
 4. The packaging article of claim 3, wherein thefluoropolymer material is polyvinylidene fluoride (PVDF).
 5. Thepackaging article of claim 1, further comprising a label disposed on anouter surface of the body, the label listing cleanliness levels.
 6. Thepackaging article of claim 1, wherein the clean item is an opticalcomponent.
 7. A packaging article for storage of clean items having aninterior surface having: less than 1×10¹⁰ atoms/cm² of each of thefollowing metals: aluminum, calcium, copper, iron, magnesium, potassium,sodium, and zinc; less than 1×10¹⁰ ions/cm² for each of the followinganions: fluoride, chloride, nitrite, sulfate, and phosphate; and lessthan 2 nanogram/cm² of each of the following organic compounds:compounds with seven to ten carbon atoms, compounds with eleven totwenty carbon atoms, and compounds with greater than 20 carbon atoms,the packaging article being produced by placing the packaging article incontact with a solution comprising an organic solvent, rinsing thepackaging article with ultrapure water; placing the packaging article incontact with an acid solution, rinsing the packaging article withultrapure water; and drying the packaging article.
 8. The packagingarticle of claim 7, wherein the packaging article further has: less than1 nanogram/cm² of each of the following organic compounds: compoundswith seven to ten carbon atoms, compounds with eleven to twenty carbonatoms, compounds with greater than 20 carbon atoms; less than 1particle/cm² for particles greater than 5 micron in size; less than 10particles/cm² for particles 1 micron to 5 micron in size; and less than100 particles/cm² for particles 0.5 micron to 1 micron in size.
 9. Thepackaging article of claim 7, wherein the packaging article is selectedfrom the group consisting of perfluoroalkoxy (PFA),polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP),perfluoropolyether (PFPE), and polyvinylidene fluoride (PVDF).
 10. Thepackaging article of claim 9, wherein the packaging article ispolyvinylidene fluoride (PVDF).
 11. The packaging article of claim 1,further comprising a label disposed thereon, the label listingcleanliness levels.
 12. The packaging article of claim 1, wherein theclean item is an optical component.
 13. The packaging article of claim1, wherein the packaging article for storage of clean items is an innerpackaging bag.
 14. The inner packaging bag of claim 13 having a siliconwafer disposed therein.
 15. The inner packaging bag of claim 14 in whichan opening in the inner packaging bag has been sealed shut.
 16. Theinner packaging bag of claim 15 further disposed within an outercontainer.